Dude, OCD much?The first post on this topic did not explain WHY the OP wanted to swap barrels on his brand new RRA midlength LAR-15. I was trying to pick his brain as to why he felt compelled to change out a brand new barrel. I was thinking that perhaps he heard that chrome lining is a military requirement and that chrome lining is a key buzzword when selecting an AR. My point was that the military's reasons for specifying chrome lining are based on different needs and conditions compared to civilians. A soldier may submerge his rifle in a river crossing, carry it in damp jungle conditions, delay cleaning it in times of battle, or store it in suboptimal non-climate controlled conditions. A civilian will generally pamper his rifle and clean it regularly. To chrome a barrel, it must be over-bored as the chroming process adds material. This added layer may or may not be the correct thickness to correct the over-bore. The chrome tends to fill in some of the rifling and can be uneven. True, a properly chrome lined barrel may last longer, but a well-maintained chromoly steel barrel will last a very very long time.
Rock River Arms has their barrels made by Wilson with a 1 MOA accuracy guaranty on the OP's model. Not many mass producers of AR have an accuracy guaranty, which speaks for the high quality of RRA barrels. I don't think it is necessary to replace the barrel on this basically unfired rifle, unless it eventually does wear out (in a few civilain lifetimes, perhaps, at today's ammo prices).